Transanal Repair
Ann C. Lowry
Indications/ContraindicationsRectovaginal fistulas, communications between the rectum and the vagina, may occur at any level of the vagina. Most commonly, the fistula originates low in the rectum and ends in the lower portion of the vagina. Obstetrical trauma, infection, and inflammatory bowel disease are the most common etiologies but some fistulas are congenital while others result from malignancy, radiation, or operative trauma.
Although rectovaginal fistulas caused by obstetrical trauma may close within the first few months postpartum, the majority of these fistulas require operative repair. Low, relatively small fistulas caused by infection or trauma are amenable to local repairs without diversion. They may be approached through the rectum, vagina, or perineum. More complex fistulas often require the interposition of muscles under the protection of temporary diversion. Such fistulas include ones located high in the rectum, caused by inflammatory bowel disease, radiation or malignancy, or large in size.
The choice of the local repair depends upon the status of the anal sphincter and the surrounding tissues. Given the nature of the injury, many women with a rectovaginal fistula caused by an obstetrical injury will also have an anterior sphincter defect. Without appropriate evaluation, sphincter dysfunction may be difficult to detect clinically as the passage of flatus and stool through the vagina may mask the symptoms of fecal incontinence. If a sphincter defect is identified then a transperineal repair is more appropriate than a transanal approach.
If there is no associated sphincter defect, the choice between a transvaginal and transanal approach for the initial repair is largely the surgeon’s preference. Proponents of the transanal approach argue that the rectum is the high pressure side, so a secure repair of that side is critical to success.
The condition of the rectum and surrounding tissue must also be considered. Repair should be avoided if active infection or inflammation is present within the rectum or the perianal tissue. Perianal sepsis should be adequately drained; in many instances, a noncutting seton is helpful in controlling sepsis and allowing a surrounding cavity to close. An alternative approach should be chosen if an anal or rectal stricture or significant scarring is identified in the rectal wall. In patients with Crohn’s disease, a transanal approach is contraindicated in the presence of active proctitis. Even without active proctitis, surgical repair of a rectovaginal fistula in a woman with Crohn’s disease
should be carefully considered. Successful control of symptoms is reported with medical management using azathioprine, metronidazole, and more recently with biologic medication. Given the high rate of recurrence and the possibility of worsening of the patient’s symptoms after surgery, repair should only be undertaken in women who have failed other options and still have significant symptoms without active proctitis.
should be carefully considered. Successful control of symptoms is reported with medical management using azathioprine, metronidazole, and more recently with biologic medication. Given the high rate of recurrence and the possibility of worsening of the patient’s symptoms after surgery, repair should only be undertaken in women who have failed other options and still have significant symptoms without active proctitis.
Preoperative PlanningWhile the passage of flatus or stool through the vagina is pathognomonic of a rectovaginal fistula, the presence and anatomy of the fistula must be confirmed before surgery. In addition, evaluation of the anal sphincter and bowel symptoms must be complete. The underlying etiology largely determines the specific investigations required.
A careful history is necessary to determine the preoperative evaluation needed. Any history of anorectal or gynecologic malignancy should prompt a thorough investigation for recurrence, both in the rectovaginal septum and pelvis. Prior treatment with radiation should be specifically elicited. Issues related to continence should also be documented. Patients with a history of a difficult delivery or previous anorectal surgery are at significant risk of a sphincter defect. One study found that 100% of women presenting with an obstetric rectovaginal fistula had evidence of an anterior sphincter defect (1). Bowel function as well as signs/symptoms of inflammatory bowel disease should also be targeted as possible areas for workup.
The site of a rectovaginal fistula can usually be readily identified during digital examination as a palpable dimple in the anterior midline. The rectal opening is frequently visible on anoscopy, but in some women the diagnosis may be elusive. A methylene blue test may confirm the presence of a communication and aid in locating the site. During this test, the patient is placed in prone position and a vaginal tampon is inserted; a 20–30 ml enema colored with methylene blue is then administered. Staining on the tampon is diagnostic of a rectovaginal fistula, assuming no spillage of dye. If this test does not confirm a fistula, an examination under anesthesia or radiologic evaluation is necessary.
The examiner should also look for findings suggestive of Crohn’s disease and/or any evidence of local sepsis. Findings of fluctuance, cellulitis, or any other signs of active infection should prompt an examination under anesthesia and drainage with or without placement of seton(s) or drain(s). Any mass discovered on examination should be biopsied to exclude malignancy. In patients with a prior history of anorectal or gynecologic malignancy, the threshold for a biopsy should be especially low. In patients with a history of radiation treatment for malignancy, an examination under anesthesia with biopsies is often necessary. Assessment of a patient’s sphincter function including resting tone, presence of circumferential motion, and change in tone when asked to squeeze should be included in the examination.
Radiographic tests may help identify an elusive fistula. Vaginography may detect a fistula and demonstrate the anatomy. The test is performed by instilling contrast into the vagina through a catheter with the balloon inflated to occlude the vaginal opening. The technique has a sensitivity of 79–100% for the detection of the fistula tract. Vaginography is most helpful for colovaginal and enterovaginal fistulae; it is less useful for low rectovaginal fistulae (2,3).
Computed tomography scans may identify the fistula tract and characterize the surrounding tissue. Contrast material in the vagina after oral or rectal administration is diagnostic of a fistula. Suggestive evidence includes air or fluid in the vagina if there is no history of recent instrumentation. Magnetic resonance imaging (MRI) and endorectal ultrasound are also useful in identifying fistulae; the injection of hydrogen peroxide into fistulae has been shown to increase the yield of ultrasonography (4). Vaginal gel inserted prior to a pelvic MRI may be beneficial. At present, there is no clear gold standard test to detect elusive fistulae.
Endoanal ultrasound and MRI also have a role in assessing the structural integrity of the anal sphincter (Fig. 10.1). Comparison of endoanal ultrasound and MRI reveals
them to be essentially equivalent in detection of a sphincter defect (5). If a limited sphincter injury is identified, anorectal physiology may be helpful in determining whether sphincter repair should be part of the chosen procedure.
them to be essentially equivalent in detection of a sphincter defect (5). If a limited sphincter injury is identified, anorectal physiology may be helpful in determining whether sphincter repair should be part of the chosen procedure.
 Figure 10.1 An ultrasound demonstrating a thin perineal body, anterior defect in the internal anal sphincter and external anal sphincter muscles. |
Evaluation of the intestinal tract by colonoscopy and contrast studies is indicated in patients with known or suspected inflammatory bowel disease.
SurgeryOptions for Transanal Repairs
Transanal approaches are appropriate choices for the repair of rectovaginal fistulas without associated anal sphincter injuries. While multiple transanal techniques for repair of rectovaginal fistulas exist in the literature, three of those techniques will be discussed in this chapter. Endorectal advancement flaps have the longest history, with the most data available. However, there are reports of postoperative incontinence with that approach (6,7,8). In attempt to avoid that complication, two recently described techniques, insertion of a fistula plug and the LIFT (ligation of intersphincteric fistula tract) are gaining popularity.
The preoperative preparation and positioning are similar for all three procedures.
Preoperative Preparation
Smoking is associated with a higher failure rate for repairs of complex anal fistulas (9,10). Although there is no definite evidence proving benefit, theoretically cessation of smoking would be beneficial. Patients undergo a mechanical bowel preparation prior to surgery to try to reduce the risk of sepsis and postoperative constipation; that recommendation is based upon clinical experience rather than high-level evidence. Intravenous antibiotics are administered immediately prior to the surgery. Oral antibiotics are not utilized. A urinary catheter is not routinely utilized.
Anesthesia and Positioning
General, regional, and local anesthesia with sedation may be used effectively for these procedures. Many surgeons prefer general anesthesia for improved patient comfort in the prone position. The patient is placed in the prone jackknife position with her hips
over a padded roll. The arms are typically on padded arm boards with the patient’s arms extended. The buttocks are taped apart for exposure. The prone position allows optimal exposure of the surgical field and comfortable access for the surgeon and assistant; a headlight aids visualization significantly.
over a padded roll. The arms are typically on padded arm boards with the patient’s arms extended. The buttocks are taped apart for exposure. The prone position allows optimal exposure of the surgical field and comfortable access for the surgeon and assistant; a headlight aids visualization significantly.
Technique
Endorectal Advancement Flap
Advancement flaps aim to eradicate rectovaginal fistula by occluding the internal opening of the tract with healthy tissue. Using a bivalve anoscope for exposure, a probe is passed from the vagina to identify the internal opening (Fig. 10.2). Starting just distal to the internal opening of the fistula, a U-shaped flap is outlined with electrocautery. The base of the flap should be 2–3 times as wide as the apex to ensure adequate blood supply of the flap (Fig. 10.3). The dissection commences distally and includes mucosa, submucosa, and circular muscle (Fig. 10.4). If the flap is too thin, the blood supply may be jeopardized. Continuing in this plane, the flap is raised for a distance sufficient to allow a tension-free repair, usually 4–5 cm (Fig. 10.5). Care should be taken to avoid creating a hole in the flap. With adequate mobilization, the distal end of the flap should easily lay at the anal verge. The fistula tract is then debrided, not excised. The internal sphincter muscle lateral to the incision is bilaterally freed from the overlying anoderm and the underlying external sphincter muscle for a short distance. The edges of the internal sphincter muscle are approximated over the fistula opening with long-acting absorbable suture in one or two layers (Fig. 10.6). Hemostasis is carefully achieved to avoid a hematoma. The distal end of the flap including the fistula site is trimmed and the flap sutured in place with interrupted 3-0 absorbable sutures (Fig. 10.7). The vaginal side is left open for drainage.
Insertion of Fistula Plug
In 2007, the results of a consensus conference regarding the anal fistula plug were published. The following technique describes the determined best practices (11). Using an anoscope for exposure, a probe is passed from the vagina to identify the internal opening (Fig. 10.2). Irrigation of the tract with either saline or diluted hydrogen peroxide is recommended. Debridement, curettage, or excision of the tract is discouraged other than if the
internal opening is epithelialized. In that situation, limited mobilization and debridement of the mucosal edges may be considered before suture placement. The plug should be prepared according to the manufacturer’s instructions. One end of the suture is tied to the probe and the other to the narrow end of the plug. Using the suture as a guide, the plug is then gently passed from the internal opening to the external opening until the plug is snug in the tract (Fig. 10.8
internal opening is epithelialized. In that situation, limited mobilization and debridement of the mucosal edges may be considered before suture placement. The plug should be prepared according to the manufacturer’s instructions. One end of the suture is tied to the probe and the other to the narrow end of the plug. Using the suture as a guide, the plug is then gently passed from the internal opening to the external opening until the plug is snug in the tract (Fig. 10.8
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